1. Field of the Invention
The present application discloses a process for casting dimensionally accurate reproductions of a pattern wherein a minimum amount of sand is used. The disclosed process may be effectively implemented in a continuous operation wherein all components of the mold assembly are manually or automatically transported to the various work stations in accordance with the disclosed process.
2. Discussion of the Prior Art
U.S. Pat. No. 3,242,539 (Lubalin) discloses a metal casting process wherein patterns are adjacently positioned on a flat metal base plate. A contoured backing flask assembly, containing a pair of hingedly connected contour cavities dimensioned to fit over the pattern plate assembly, is then superposed over the patterns. Thus, a predetermined relatively thin open faced cavity exists between the interior surface of the backing flask cavities and the external surface of the patterns, which cavity corresponds to the desired thickness of the ceramic that will line the mold. A volatile alcohol or water-containing ceramic slurry is then poured into pouring apertures formed in the flask so that the cavity is filled. The rigid backing flask assembly and jelled ceramic is removed from the pattern and the flask and ceramic liner are fired to burn off volatiles and set the ceramic. After the flask is cooled, the hinged flask assembly is closed to define a lined mold cavity therebetween. The desired metal is then poured into the cavity.
The Lubalin process is not readily adapted to a quick and efficient continuous process, however, since the disclosed use of the ceramic slurry mandates that relatively long drying and firing steps be completed in order to properly set the ceramic. Further, use of a ceramic slurry often results in the formation of gas bubbles which, after firing, result in an uneven and sometimes cracked refractory lining causing poor overall casting quality. Also, the disclosed hinged flask assembly itself is heavy and quite expensive to handle and transport about the foundry.
Prior art U.S. Pat. No. 2,789,331 (Dietert) discloses another method of making molds for casting wherein a refractory lining is produced by blowing the refractory into the space provided between a pattern and a drying plate. After firing and cooling of the refractory, the hardened refractory is stripped from the pattern and drying plate assembly and then positioned adjacent a mating refractory to define a mold cavity therebetween. The mating refractories are inserted in a vice like mechanism so that they are firmly held together. Here again, the disclosed process cannot be effectively adapted to a quick continuous process because of the time consuming steps of stripping the refractory from its associated pattern and drying plate followed by combining mating refractories to the vice prior to pouring.
Other mold and casting formation processes are disclosed in U.S. Pat. Nos.:
______________________________________ 2,837,798 (Bleuenstein) 2,940,140 (Frantz) 3,136,011 (Peras) ______________________________________
All of the above mentioned prior art patents are deficient with respect to the provision of a quick and continuous casting process wherein material handling costs are minimized. Further, in most of these prior art processes, large amounts of sand, sometimes on the order of one half to one ton sand per ton of resulting castings, must be used, thus necessitating utilization of expensive reclamation equipment. The prior art processes also require the use of heavy flask assemblies that are both burdensome and expensive to transport about the foundry.
These and other deficiencies of the prior art are overcome by use of the process disclaimed herein--which provides a relatively quick casting process that is ideally implemented in a continuous manner, with only minor interruptions between certain work stations being present. The equipment itself is relatively lightweight and can be readily transported about the foundry by movable hoists, wheeled assemblies, and the like. The process results in the formation of highly accurate castings with economies being realized in the areas of materials handling and equipment investment.
The foregoing and other advantages realized by the present process will become further apparent in the following detailed description, which is effectively amplified in the accompanying drawings.